/*  
 * i-OSGi - Tunable Bundle Isolation for OSGi
 * Copyright (C) 2011  Sven Schulz
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.iosgi.impl.engine;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import de.timefinder.algo.roomassignment.HungarianAlgorithm;

/**
 * @author Sven Schulz 
 */
public class SetMatching {

	public static <T> Map<Integer, Integer> findBestMatch(List<Set<T>> a,
			List<Set<T>> b) {
		float[][] distances = new float[a.size()][b.size()];
		for (int i = 0; i < a.size(); i++) {
			for (int j = 0; j < b.size(); j++) {
				distances[i][j] = distance(a.get(i), b.get(j));
			}
		}
		HungarianAlgorithm ha = new HungarianAlgorithm();
		int[][] assignments = ha.computeAssignments(distances);
		Map<Integer, Integer> result = new HashMap<Integer, Integer>();
		for (int i = 0; i < assignments.length; i++) {
			result.put(assignments[i][0], assignments[i][1]);
		}
		return result;
	}

	static <T> int distance(Set<T> a, Set<T> b) {
		int distance = 0;
		for (T e : a) {
			if (!b.contains(e)) {
				distance++;
			}
		}
		for (T e : b) {
			if (!a.contains(e)) {
				distance++;
			}
		}
		return distance;
	}

}